# MinIO 예시

MinIO Operator + Tenant CRD (`minio.min.io/v2`) + KES + Vault transit 기준. 모든 manifest는 `kubectl apply` 적용 가능한 완전한 형태다.

---

## 좋은 예시 1: Namespace + Tenant configuration Secret

```yaml
---
apiVersion: v1
kind: Namespace
metadata:
  name: minio-prod
  labels:
    pod-security.kubernetes.io/enforce: restricted
    pod-security.kubernetes.io/audit: restricted
    app.kubernetes.io/part-of: storage-platform
---
apiVersion: v1
kind: Secret
metadata:
  name: minio-tenant-env
  namespace: minio-prod
type: Opaque
stringData:
  config.env: |
    export MINIO_ROOT_USER="REPLACE_VIA_VSO"
    export MINIO_ROOT_PASSWORD="REPLACE_VIA_VSO"
    export MINIO_STORAGE_CLASS_STANDARD="EC:4"
    export MINIO_STORAGE_CLASS_RRS="EC:2"
    export MINIO_BROWSER_REDIRECT_URL="https://minio-console.internal.example.com"
    export MINIO_SERVER_URL="https://s3.example.com"
    export MINIO_IDENTITY_OPENID_CONFIG_URL="https://auth.example.com/realms/platform/.well-known/openid-configuration"
    export MINIO_IDENTITY_OPENID_CLIENT_ID="minio"
    export MINIO_IDENTITY_OPENID_CLAIM_NAME="policy"
    export MINIO_IDENTITY_OPENID_SCOPES="openid,profile,email"
    export MINIO_PROMETHEUS_AUTH_TYPE="jwt"
---
# 실 운영에서는 VSO가 이 Secret을 채움
apiVersion: secrets.hashicorp.com/v1beta1
kind: VaultStaticSecret
metadata:
  name: minio-root-creds
  namespace: minio-prod
spec:
  vaultAuthRef: default
  mount: kv
  path: minio/prod/root
  type: kv-v2
  refreshAfter: 24h
  destination:
    name: minio-tenant-env
    create: false
    overwrite: true
    transformation:
      excludeRaw: true
      templates:
        config.env:
          text: |
            export MINIO_ROOT_USER="{{ .Secrets.username }}"
            export MINIO_ROOT_PASSWORD="{{ .Secrets.password }}"
            export MINIO_STORAGE_CLASS_STANDARD="EC:4"
            export MINIO_BROWSER_REDIRECT_URL="https://minio-console.internal.example.com"
            export MINIO_SERVER_URL="https://s3.example.com"
            export MINIO_IDENTITY_OPENID_CONFIG_URL="https://auth.example.com/realms/platform/.well-known/openid-configuration"
            export MINIO_IDENTITY_OPENID_CLIENT_ID="minio"
            export MINIO_IDENTITY_OPENID_CLIENT_SECRET="{{ .Secrets.oidc_client_secret }}"
            export MINIO_IDENTITY_OPENID_CLAIM_NAME="policy"
            export MINIO_IDENTITY_OPENID_SCOPES="openid,profile,email"
            export MINIO_PROMETHEUS_AUTH_TYPE="jwt"
```

**왜 좋은가:**

- Tenant configuration은 **shell-source 형식**(`export KEY=VALUE`) Secret으로 전달 (Operator 규약)
- Root credential을 Vault KV에서 VSO가 주입 — Git에 평문 없음
- OIDC 통합 (Keycloak), storage class EC:4, Prometheus JWT auth 한 파일에 고정
- `MINIO_SERVER_URL`로 외부 S3 endpoint 명시 (presigned URL 생성 시 사용)

---

## 좋은 예시 2: Tenant CR — 4 server × 4 volume + KES + TLS

```yaml
apiVersion: minio.min.io/v2
kind: Tenant
metadata:
  name: minio
  namespace: minio-prod
  labels:
    app.kubernetes.io/name: minio
    app.kubernetes.io/instance: minio-prod
    app.kubernetes.io/part-of: storage-platform
    app.kubernetes.io/managed-by: minio-operator
  annotations:
    prometheus.io/path: /minio/v2/metrics/cluster
    prometheus.io/port: "9000"
    prometheus.io/scrape: "true"
spec:
  image: quay.io/minio/minio:RELEASE.2025-01-20T14-49-07Z
  imagePullPolicy: IfNotPresent
  mountPath: /export

  configuration:
    name: minio-tenant-env

  requestAutoCert: true
  certConfig:
    commonName: minio.minio-prod.svc.cluster.local
    organizationName:
      - example.com
    dnsNames:
      - minio.minio-prod.svc.cluster.local
      - "*.minio-hl.minio-prod.svc.cluster.local"
      - s3.example.com

  pools:
    - name: pool-0
      servers: 4
      volumesPerServer: 4
      volumeClaimTemplate:
        metadata:
          name: data
        spec:
          accessModes:
            - ReadWriteOnce
          resources:
            requests:
              storage: 500Gi
          storageClassName: local-xfs-retain
      resources:
        requests:
          cpu: 500m
          memory: 2Gi
        limits:
          cpu: "4"
          memory: 8Gi
      securityContext:
        runAsUser: 1000
        runAsGroup: 1000
        runAsNonRoot: true
        fsGroup: 1000
        fsGroupChangePolicy: OnRootMismatch
        seccompProfile:
          type: RuntimeDefault
      containerSecurityContext:
        runAsUser: 1000
        runAsGroup: 1000
        runAsNonRoot: true
        allowPrivilegeEscalation: false
        readOnlyRootFilesystem: true
        capabilities:
          drop:
            - ALL
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            - labelSelector:
                matchLabels:
                  v1.min.io/tenant: minio
                  v1.min.io/pool: pool-0
              topologyKey: kubernetes.io/hostname
      topologySpreadConstraints:
        - maxSkew: 1
          topologyKey: topology.kubernetes.io/zone
          whenUnsatisfiable: ScheduleAnyway
          labelSelector:
            matchLabels:
              v1.min.io/tenant: minio
      tolerations:
        - key: storage
          operator: Equal
          value: dedicated
          effect: NoSchedule

  features:
    bucketDNS: false
    domains:
      console: https://minio-console.internal.example.com
      minio:
        - https://s3.example.com

  kes:
    image: quay.io/minio/kes:2025-01-16T16-24-39Z
    replicas: 2
    kesSecret:
      name: kes-configuration
    imagePullPolicy: IfNotPresent
    resources:
      requests:
        cpu: 100m
        memory: 128Mi
      limits:
        cpu: 500m
        memory: 512Mi
    securityContext:
      runAsUser: 1000
      runAsGroup: 1000
      runAsNonRoot: true
      fsGroup: 1000
    containerSecurityContext:
      runAsNonRoot: true
      allowPrivilegeEscalation: false
      readOnlyRootFilesystem: true
      capabilities:
        drop:
          - ALL

  prometheusOperator: true

  podManagementPolicy: Parallel

  exposeServices:
    minio: true
    console: false

  logging:
    anonymous: false
    json: true
    quiet: false
---
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: minio
  namespace: minio-prod
spec:
  minAvailable: 3
  unhealthyPodEvictionPolicy: AlwaysAllow
  selector:
    matchLabels:
      v1.min.io/tenant: minio
```

**왜 좋은가:**

- `servers × volumesPerServer = 4 × 4 = 16` drive → erasure coding 최소 요건 충족, `EC:4` 기본 parity (4 drive 장애 허용)
- `requestAutoCert: true` + `certConfig.dnsNames`로 Operator가 API/Console TLS 자동 발급
- `podAntiAffinity` hostname required → 한 node에 MinIO pod 복수 배치 금지 (EC 의미 보존)
- KES가 별도 2 replica로 사이드카 없이 Deployment로 분리 (Tenant CR에서 관리됨)
- `exposeServices.console: false` → Console은 Tenant Service에서 Ingress로 별도 처리만 허용
- `minAvailable: 3` → 4 server 중 1 동시 drain까지 허용 (write quorum 보존)

---

## 나쁜 예시 1: 단일 Deployment로 MinIO

```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: minio
spec:
  replicas: 1
  template:
    spec:
      containers:
        - name: minio
          image: minio/minio
          args: ["server", "/data"]
          env:
            - name: MINIO_ROOT_USER
              value: minioadmin
            - name: MINIO_ROOT_PASSWORD
              value: minioadmin
          volumeMounts:
            - name: data
              mountPath: /data
      volumes:
        - name: data
          emptyDir: {}
```

**문제:**

- Single-drive MinIO → erasure coding 없음, 1 drive 장애 = 전체 data loss
- Deployment = 재시작 시 PVC binding 보장 없음, 복수 replica 시 동일 volume 충돌
- emptyDir → pod 재시작 시 모든 object 사라짐
- 기본 `minioadmin/minioadmin` credential → 공개 인터넷 스캐너가 수 분 내 탈취
- Operator + Tenant가 자동화하는 인증서, 서비스, headless, auto-restart를 전부 수제로 다시 만들어야 함

---

## 좋은 예시 3: KES configuration + Vault transit

```yaml
---
apiVersion: v1
kind: Secret
metadata:
  name: kes-configuration
  namespace: minio-prod
type: Opaque
stringData:
  server-config.yaml: |
    version: v1
    address: 0.0.0.0:7373

    admin:
      identity: disabled

    tls:
      key:  /tmp/kes/server.key
      cert: /tmp/kes/server.cert

    policy:
      minio-app:
        allow:
          - /v1/key/create/minio-*
          - /v1/key/generate/minio-*
          - /v1/key/decrypt/minio-*
          - /v1/key/bulk/decrypt/minio-*
          - /v1/key/list/minio-*
          - /v1/status
          - /v1/metrics
          - /v1/api
        identities:
          - ${MINIO_KES_IDENTITY}

    keystore:
      vault:
        endpoint: https://vault.vault.svc.cluster.local:8200
        engine: transit
        version: v1
        namespace: ""
        prefix: minio
        approle:
          id: ${VAULT_APPROLE_ID}
          secret: ${VAULT_APPROLE_SECRET}
          retry: 15s
        tls:
          ca: /tmp/kes/vault-ca.crt
        status:
          ping: 10s
---
# Vault AppRole credential은 VSO 또는 별도 Secret으로 주입
apiVersion: secrets.hashicorp.com/v1beta1
kind: VaultStaticSecret
metadata:
  name: kes-vault-approle
  namespace: minio-prod
spec:
  vaultAuthRef: default
  mount: kv
  path: minio/kes/approle
  type: kv-v2
  refreshAfter: 24h
  destination:
    name: kes-vault-approle
    create: true
    overwrite: true
```

그리고 bucket에 SSE-KMS 적용:

```bash
mc alias set minio https://s3.example.com $ROOT_USER $ROOT_PASS

# Vault transit에 key 생성
mc admin kms key create minio minio-critical

# bucket에 SSE-KMS 기본 적용
mc encrypt set sse-kms minio-critical minio/critical-bucket
```

**왜 좋은가:**

- KES가 Vault transit을 key store로 사용 → master key는 Vault가 관리, MinIO는 DEK만 캐시
- KES policy로 `minio-*` prefix key만 access 허용 (최소 권한)
- AppRole credential은 Vault → VSO → Secret 경로
- bucket level SSE-KMS → 업로드되는 모든 object가 per-object DEK로 자동 암호화

---

## 나쁜 예시 2: KES 없이 평문 저장

```yaml
# Tenant CR
spec:
  kes: {}  # 미설정
  # ... SSE 설정 없음
```

```bash
mc cp secret.pdf minio/bucket/secret.pdf
# object가 disk에 평문 저장
```

**문제:**

- PVC가 탈취되거나 물리 drive가 반출되면 평문 유출
- 감사/규제 요구(GDPR, PCI-DSS, ISO 27001) 위반
- SSE-S3를 대신 쓰더라도 master key가 MinIO 자체에 있어 키 라이프사이클 관리 불가

---

## 좋은 예시 4: Probe — live + cluster-read

Tenant CR이 자동으로 probe를 구성하지만, 커스텀 오버라이드가 필요할 때:

```yaml
spec:
  pools:
    - name: pool-0
      # ...
      containers:
        - name: minio
          livenessProbe:
            httpGet:
              path: /minio/health/live
              port: 9000
              scheme: HTTPS
            initialDelaySeconds: 60
            periodSeconds: 30
            timeoutSeconds: 5
            failureThreshold: 3
          readinessProbe:
            httpGet:
              path: /minio/health/cluster/read
              port: 9000
              scheme: HTTPS
            periodSeconds: 10
            timeoutSeconds: 5
            failureThreshold: 3
          startupProbe:
            httpGet:
              path: /minio/health/live
              port: 9000
              scheme: HTTPS
            periodSeconds: 5
            failureThreshold: 60
            timeoutSeconds: 5
```

**왜 좋은가:**

- `readinessProbe`는 `/minio/health/cluster/read` → **read quorum** 검사. rolling update 중에도 read가 가능하면 Service에 남아있음
- `/minio/health/cluster` (write quorum)을 readiness로 쓰면 rolling 재시작 시 pod가 전부 빠져 완전 unavailable
- `livenessProbe`는 단순 프로세스 생존만 확인 → 일시적 quorum 상실로 pod 강제 재시작 방지
- HTTPS scheme (requestAutoCert과 일치)

---

## 나쁜 예시 3: readiness를 write quorum으로

```yaml
readinessProbe:
  httpGet:
    path: /minio/health/cluster
    port: 9000
  periodSeconds: 5
  failureThreshold: 1
```

**문제:**

- rolling update로 pod 1개를 재시작하면 write quorum이 일시적으로 무너져 살아있는 pod들도 NotReady
- Service가 endpoint를 전부 제거 → **읽기도 불가능**
- `failureThreshold: 1` + 5초 주기 → 한 번 느린 응답으로 pod 빠짐

---

## 좋은 예시 5: Ingress — API는 공개, Console은 내부

```yaml
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: minio-api
  namespace: minio-prod
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/proxy-body-size: "0"
    nginx.ingress.kubernetes.io/proxy-request-buffering: "off"
    nginx.ingress.kubernetes.io/proxy-buffering: "off"
    nginx.ingress.kubernetes.io/backend-protocol: HTTPS
spec:
  ingressClassName: nginx
  tls:
    - hosts:
        - s3.example.com
      secretName: minio-api-ingress-tls
  rules:
    - host: s3.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: minio
                port:
                  number: 443
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: minio-console
  namespace: minio-prod
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/whitelist-source-range: "10.0.0.0/8,192.168.0.0/16"
    nginx.ingress.kubernetes.io/auth-url: "https://oauth2-proxy.example.com/oauth2/auth"
    nginx.ingress.kubernetes.io/backend-protocol: HTTPS
spec:
  ingressClassName: nginx-internal
  tls:
    - hosts:
        - minio-console.internal.example.com
      secretName: minio-console-ingress-tls
  rules:
    - host: minio-console.internal.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: minio-console
                port:
                  number: 9443
```

**왜 좋은가:**

- API Ingress는 `proxy-body-size: 0` + request/response buffering off → 대용량 multipart upload 지원
- Console은 내부 ingress class + IP whitelist + OIDC forward-auth 2중 보호
- `backend-protocol: HTTPS` → MinIO의 auto-cert TLS를 TLS passthrough 형태로 전달 (인증서 SAN 보존)

---

## 나쁜 예시 4: Console 외부 공개

```yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: minio-all
spec:
  rules:
    - host: minio.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: minio
                port:
                  number: 9090
```

**문제:**

- Console이 인터넷에 그대로 노출 → root/admin credential brute force 표면 확장
- OIDC forward-auth 없음 → 기본 login 페이지가 공격자에게 노출
- IP 제한 없음
- Bucket 목록, access key 관리, 사용자 관리가 모두 공개 domain에 위치

---

## 좋은 예시 6: ServiceMonitor (Prometheus bearer-token)

먼저 MinIO 내부에서 scrape token 발급:

```bash
mc admin prometheus generate minio cluster
# 출력에 bearer token과 scrape config가 나옴
```

그 결과 token을 Secret로 저장:

```yaml
---
apiVersion: v1
kind: Secret
metadata:
  name: minio-prometheus-token
  namespace: minio-prod
type: Opaque
stringData:
  token: "<minio-prometheus-token>"
---
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: minio
  namespace: minio-prod
  labels:
    app.kubernetes.io/name: minio
    release: kube-prometheus-stack
spec:
  selector:
    matchLabels:
      v1.min.io/tenant: minio
  endpoints:
    - port: https-minio
      scheme: https
      path: /minio/v2/metrics/cluster
      interval: 30s
      scrapeTimeout: 10s
      bearerTokenSecret:
        name: minio-prometheus-token
        key: token
      tlsConfig:
        insecureSkipVerify: false
        ca:
          secret:
            name: minio-tls
            key: ca.crt
        serverName: minio.minio-prod.svc.cluster.local
```

**왜 좋은가:**

- `MINIO_PROMETHEUS_AUTH_TYPE=jwt` 와 매칭 (기본값)
- `/minio/v2/metrics/cluster`는 cluster-wide view (replication lag, bucket 사용량, API latency)
- TLS 검증 유지 (`insecureSkipVerify: false`, CA bundle 제공)
- 외부 노출 없이 내부 scrape만

---

## 좋은 예시 7: Bucket 초기화 (Job) — versioning + Object Lock + lifecycle

```yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: minio-bootstrap
  namespace: minio-prod
data:
  init.sh: |
    #!/bin/sh
    set -eu

    mc --config-dir /tmp/mc alias import minio <<EOF
    {
      "url": "https://minio.minio-prod.svc.cluster.local",
      "accessKey": "$MINIO_ROOT_USER",
      "secretKey": "$MINIO_ROOT_PASSWORD",
      "api": "s3v4",
      "path": "auto"
    }
    EOF

    # Object Lock은 bucket 생성 시점에만 활성화 가능
    mc --config-dir /tmp/mc mb --with-lock minio/critical-audit || true
    mc --config-dir /tmp/mc retention set --default COMPLIANCE 2555d minio/critical-audit

    # Versioning + lifecycle
    mc --config-dir /tmp/mc mb minio/app-data || true
    mc --config-dir /tmp/mc version enable minio/app-data
    mc --config-dir /tmp/mc ilm add --expire-noncurrent-days 90 minio/app-data
    mc --config-dir /tmp/mc ilm add --expire-incomplete-upload-days 7 minio/app-data

    # SSE-KMS 기본 적용
    mc --config-dir /tmp/mc encrypt set sse-kms minio-app-key minio/app-data
    mc --config-dir /tmp/mc encrypt set sse-kms minio-critical-key minio/critical-audit

    echo "bootstrap complete"
---
apiVersion: batch/v1
kind: Job
metadata:
  name: minio-bootstrap
  namespace: minio-prod
spec:
  backoffLimit: 3
  ttlSecondsAfterFinished: 86400
  template:
    spec:
      restartPolicy: OnFailure
      serviceAccountName: minio-bootstrap
      containers:
        - name: mc
          image: quay.io/minio/mc:RELEASE.2025-01-17T23-25-50Z
          command: ["/bin/sh", "/scripts/init.sh"]
          resources:
            requests: { cpu: 100m, memory: 128Mi }
            limits:   { memory: 256Mi }
          env:
            - name: MINIO_ROOT_USER
              valueFrom:
                secretKeyRef:
                  name: minio-root-creds
                  key: username
            - name: MINIO_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: minio-root-creds
                  key: password
          volumeMounts:
            - name: scripts
              mountPath: /scripts
            - name: tmp
              mountPath: /tmp
          securityContext:
            runAsNonRoot: true
            runAsUser: 1000
            allowPrivilegeEscalation: false
            readOnlyRootFilesystem: true
            capabilities:
              drop:
                - ALL
      volumes:
        - name: scripts
          configMap:
            name: minio-bootstrap
            defaultMode: 0755
            items:
              - key: init.sh
                path: init.sh
        - name: tmp
          emptyDir:
            medium: Memory
            sizeLimit: 64Mi
```

**왜 좋은가:**

- `mc mb --with-lock`은 bucket 생성 시점에만 Object Lock 활성화 가능 — Job이 그 타이밍을 보장
- COMPLIANCE 모드 7년 retention = 감사/규제 요구 충족 (root도 bypass 불가)
- `app-data` bucket은 versioning + lifecycle (90일 noncurrent expire + 7일 incomplete abort)
- 애플리케이션 access key 발급은 별도 bootstrap에서 inline 최소 권한 policy와
  함께 수행하고, 생성 secret은 Vault로 직접 전달
- `backoffLimit: 3` + idempotent 명령 (`|| true`) → 재실행 안전

---

## 나쁜 예시 5: mc mirror만으로 DR

```bash
# 매일 자정 crontab
mc mirror minio/critical remote-minio/critical-backup
```

**문제:**

- `mc mirror`는 **현재 object만** 동기화 — 버전 히스토리 유실
- Object Lock 상태, bucket policy, IAM 설정 미복제
- 메타데이터 중 일부(tag, legal hold) 누락
- RPO = 1일 (하루 단위 손실), replication은 async ms 단위 RPO
- DR 연습(resync 절차) 불가

대안: `mc admin replicate add` (site replication, IAM + bucket + object 전부 async 동기화).

---

## 좋은 예시 8: Bucket replication

```bash
# source alias 설정
mc alias set source https://minio.minio-prod.svc.cluster.local $SRC_USER $SRC_PASS
mc alias set target https://minio.minio-dr.svc.cluster.local $TGT_USER $TGT_PASS

# target에 replication 전용 user + policy
mc admin policy create target replication-target /policies/replication.json
mc admin user add target replication-bot $(openssl rand -hex 16)
mc admin policy attach target replication-target --user replication-bot

# source에서 remote target 등록
mc replicate add source/app-data \
  --remote-bucket https://replication-bot:PASS@minio.minio-dr.svc.cluster.local/app-data \
  --replicate "delete,delete-marker,existing-objects,metadata-sync" \
  --priority 1
```

`replication.json`:

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "s3:GetBucketVersioning",
        "s3:PutBucketVersioning",
        "s3:GetReplicationConfiguration",
        "s3:ReplicateObject",
        "s3:ReplicateDelete",
        "s3:ReplicateTags",
        "s3:GetObjectVersion",
        "s3:GetObjectVersionTagging",
        "s3:GetObjectVersionForReplication"
      ],
      "Resource": ["arn:aws:s3:::app-data/*", "arn:aws:s3:::app-data"]
    }
  ]
}
```

**왜 좋은가:**

- `existing-objects` 옵션으로 기존 데이터 backfill
- `delete` + `delete-marker`로 삭제도 복제 (true mirror)
- 전용 replication user + 최소 권한 policy
- async 복제, bucket versioning 전제

---

## 좋은 예시 9: Keycloak OIDC STS 로그인

Keycloak에 `minio` client 생성 후:

```bash
# 앱에서 JWT를 받은 다음
curl -X POST https://s3.example.com/ \
  -d "Action=AssumeRoleWithWebIdentity" \
  -d "Version=2011-06-15" \
  -d "WebIdentityToken=${KEYCLOAK_ID_TOKEN}" \
  -d "DurationSeconds=3600"
```

응답의 `AccessKeyId`, `SecretAccessKey`, `SessionToken`을 S3 SDK에 주입.

```bash
# AWS CLI 예시
aws configure set aws_access_key_id "$STS_ACCESS_KEY"
aws configure set aws_secret_access_key "$STS_SECRET_KEY"
aws configure set aws_session_token "$STS_SESSION_TOKEN"
aws s3 ls s3://app-data/ --endpoint-url https://s3.example.com
```

**왜 좋은가:**

- 앱/사용자는 Keycloak에 로그인만 하면 됨 — MinIO에 user 등록 불필요
- 임시 credential (1시간 TTL) → 유출 시 피해 제한
- JWT의 `policy` claim이 MinIO 정책과 자동 매핑
- 장기 access key 배포 없음